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HomeAccessory Dwelling Unit Adu House PlansCharming Garage Apartment with Private Suite and Modern Amenities

Charming Garage Apartment with Private Suite and Modern Amenities

Plan #AD6378-A · 640 sq ft · 1 bd · 1 ba · 2.0 story · 2-car

Accessory Dwelling Unit Adu House PlansCarriage House Plans Garage Apartment Plans Adu DesignsCottageTwo Story
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Estimated cost to build the home
$95k – $160kFree zip estimate ↓
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David Park · Residential Plan Advisor · 30+ years
640
Sq Ft
1
Beds
1
Baths
2.0
Stories
2
Garage
8′
Ceilings
“We kept coming back to this plan — it just felt right for our family. The flow between the kitchen and living room works.”Verified buyer · Trustpilot
40+
Years in Business
3,000+
Plans in Catalog
10%
Beat Any Competitor Price
Expert
In-House Design Team
Quick self-check · 30 seconds

Is this the right plan for you?

Most regret comes from buying a plan that doesn't fit your life. Skim this before you decide.

Great fit if you…
  • Want to add rental income or guest quarters without expanding the main house (640 sq ft detached unit with private entrance)
  • Working with a small lot—the footprint is just 30 ft wide by 26 ft deep
  • Need a compact accessory dwelling unit (ADU) for aging parents or adult children (1 bedroom, 1 bathroom, fully self-contained)
  • Seeking a home office or creative studio with separate entrance (second-floor private suite)
! May not be the best fit if you…
  • Need multiple bedrooms or bathrooms—this plan has only 1 bedroom and 1 bathroom
  • Want a single-story layout—this is a two-story design with stairs to the living quarters
  • Require a large living footprint—640 sq ft is intentionally compact and efficient
  • Prefer main-floor living—the master suite and all living space are on the second floor

This plan tends to appeal to:

Accessory Dwelling Unit BuildersRental Property InvestorsAcreage OwnersWork-From-Home ProfessionalsAging-in-Place BuyersDownsizers
Think this is the one? Choose your package above and check out when you're ready.Yes — this plan fits me →

Floor Plans

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Main Level — 640 sq ft · 30.00′W × 26.00′D

↓ Free Sample
floor plan

Choose Your Package

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PDF Set
Build as-is or minor changes
$890
  • Complete working drawings (PDF)
  • Instant delivery to your email
  • Unlimited build license included
  • Copyright release — print as needed
  • AutoCAD DWG files not included
5 Prints
$990
  • Complete construction drawings
  • Unlimited build license included
  • Copyright release — print as needed
5 Prints + PDF
$995
  • Complete construction drawings
  • Unlimited build license included
  • Copyright release — print as needed
CAD Set
Significant modifications or custom design
$1,750
  • Complete construction drawings
  • Unlimited build license included
  • Copyright release — print as needed

About this plan

Adu 315 is a two-story carriage house plan providing 640 square feet of heated living area, designed specifically for versatility as an accessory dwelling unit. With a 30-foot width and 26-foot depth, this structure occupies a compact footprint that fits efficiently on diverse property configurations. The design pairs a ground-level garage with a self-contained residential unit, making it a viable option for guest quarters, rental income, or a private home studio.

The second-floor living space is organized to prioritize efficiency, featuring a primary suite equipped with a full bathroom and convenient laundry access integrated directly into the closet. The layout maintains an open-concept feel, allowing the 640 square feet of living space to accommodate essential daily needs without unnecessary partition walls. This level is designed for maximum utility, ensuring that the residential footprint remains both practical and comfortable for occupants.

Vertical volume is defined by consistent 8-foot ceiling heights on the second floor, which provide a standard vertical clearance throughout the living quarters. The structure reaches a maximum building height of 22 feet 3 inches and features an 8:12 roof pitch, contributing to a traditional exterior profile that complements existing main dwellings. The building is constructed to balance vertical scale with a manageable total height.

The ground level is dedicated to a 780 square foot 2-car garage, offering ample space for vehicle parking, storage, or a workshop area. The garage features a 9-foot ceiling height, providing vertical clearance for taller vehicles or overhead storage systems. This configuration ensures that the primary residential functions remain isolated from the garage utility space, maintaining a clean separation between the two zones.

Key Features: 1 bedroom, 1 bathroom, 640 sq ft living area, 780 sq ft 2-car garage, accessory dwelling unit, 8-foot ceiling height, 8:12 roof pitch, primary suite with laundry access, 22-foot 3-inch building height, detached carriage house design.

Explore floor plans, available formats, and modification options for this design.

What's included in this plan
  • Exterior elevations (all sides)
  • Detailed floor plan(s) with dimensions
  • Foundation plan
  • Roof plan
  • Schematic electrical layout
  • Building cross-sections
  • General notes & specifications
Not included (handled locally)
  • Architectural / engineering stamps
  • Site & grading plan
  • Structural / framing calculations
  • Plumbing & HVAC layouts
  • Energy-compliance documents
  • Material take-off list
These are typically prepared by your local builder or engineer to meet your jurisdiction's requirements.

Complete Plan Specifications

Total Living (heated)640 sq ft
2nd Floor640 sq ft
Bedrooms1
Full Bathrooms1
Stories2.0
Width of House30′
Depth of House26′
Building Height22′3″
1st Floor8′
2nd Floor8′
Garage9′
Garage2-car, front-load
Garage Area780 sq ft
FoundationSlab
Wall Framing2x6
Roof FramingStick
Roof Pitch8:12

Key Features

2.0-story layout
1 bedrooms · 1 full baths
8-ft ceilings on the main level
2-car garage
30.00′ × 26.00′ footprint
Unlimited build license included
Copyright release — print as many copies as you need
Builder-friendly construction drawings

Modify This Plan

Free quote in 1–3 business days · In-house design team
In-house design team · Family-owned since 1983

Need a 4th bedroom, a different foundation, or 8 more feet of width?

Two quick steps. We'll reply with a fixed-price quote — no obligation, and no charge until you approve.

1–3 days
To send your quote
~2 wks
Typical revision time
Free
Until you approve
Direct
To the architect
1
Your contact
2
What to change
PLAN
Plan #AD6378-A
GARAGE · 640 sq ft · 1 bd / 1 ba / 2-car

First — where should we send your quote?

We only ask for what we need to get back to you. No address, no marketing.

Free quote — no charge until you approve·Direct to our in-house architect·40+ years modifying plans

What will this cost to build?

Most buyers are off by 20–30% before checking this.
Budget
$293k
Most common
Mid-range
$340k
Premium
$382k+
Modeled on Wichita, KS — our US price-baseline city. Use the form below to generate an exact estimate for your own location.
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Still deciding?

Book a free 15-min plan review with David Park.

David has 30+ years in residential design and construction documents. He'll walk through this plan with you — foundation options for your lot, modification possibilities, and exactly what's in the construction documents you'd receive. No pitch. No fee.


Reviews across all our plans — see plan-specific reviews on Trustpilot →

★★★★★

JoAnne and the entire staff was extremely helpful and patient with us while we decided between 2 homes. Outstanding curb appeal and a great layout perfect for us.

R
Rita Long · Milwaukee, WI
Plan: Cranberry Gardens
Verified buyer · Trustpilot
★★★★★

We've had an amazing experience with our new home. The customer service we received during our modifications was exceptional — they walked us through every change.

S
Sandra Hawkins · Montgomery, AL
Plan: Dunrobin Castle
Verified buyer · Trustpilot
★★★★★

We compared three plan sources and Archival's pricing + free design call won us over. Our builder said the construction docs were the cleanest he'd seen.

M
Mark Chen · Boise, ID
Plan: Pepperwood Place
Verified buyer · Trustpilot

→ Read all 687+ reviews on Trustpilot


Frequently Asked Questions

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For most buyers, the PDF Set is the right choice — instant delivery, unlimited build license, and easy to share with your builder. If you plan significant modifications or are building in CA, OR, WA, or NV, go with CAD + PDF so your designer can edit the source files. Still not sure? Call (888) 890-2353 and a real person will help you choose.

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